i'm unable to prove the following : $\forall n$ integer $\geq 3$,
$ \displaystyle \displaystyle \sum_{s=1}^n \sum_{j=n-s+1}^n \displaystyle \frac{ (\binom n j )^2 \binom {n+j} n }{s-n+j} ( \displaystyle \sum_{t=1}^n \displaystyle \frac{1}{j+t} +2 \displaystyle \sum_{t=0,t \neq j}^n \displaystyle \frac{1}{t-j}) $ $ =\displaystyle \sum_{s=0}^n \displaystyle \sum_{r=s+1}^n \displaystyle \frac{ \binom n r \binom n s (-1)^{r+s} }{r-s} {\Big{(}} \binom {n+r} n + \binom {n+s} n {\Big{)}} \displaystyle \sum_{t=s+1}^r \frac{1}{t} $
Any help? Is that a new result?